Wetlands - What Are Wetlands? F F F Wetlands Overview...

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Wetlands Overview Randall Guenslerand Paul Chinowsky School of Civil/Environmental Engineering Georgia Institute of Technology Copyright 1997 What Are Wetlands? F General Term used to describe a variety of ecosystems F Transitional zones - dry land and open water F Wetlands: US Army Corps of Engineers and US Environmental Protection Agency – Areas of land that are [either permanently or seasonally] inundated or saturated by surface or ground water at a frequency sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in soil saturated conditions 33 CFR 328.3(b) and 40 CFR 230.3(t). Wetlands Characteristics (I) F Hydrology – Defined by water flows entering and leaving a site – Wetland sites are poorly drained, waterlogged for long periods – Water sources: rain, overland flow, rising groundwater, or any combination – Can be seasonal or perennial (permanent) Wetlands Characteristics (II) F Soils – Saturation with water results in loss of pore space to hold oxygen – Anaerobic conditions result -“ hydric soils” – Reduced microbial activity - slow decomposition of plant material – Anaerobic microbes produce awful-smelling off-gases – Anaerobic microbes reduce metals (change in valence state) making the metals water soluble and mobile (leachable) – Soils typically appear dark gray or black Wetlands Characteristics (III) F Plants u Specifically adapted to low O 2 conditions u General terminology is “Hydrophytes” u Obligates - require wetland conditions – Cattail, Tule, Water Plantain, Pondweed, etc. u Facultative Species are tolerant of wetland and non- wetland conditions (seasonal wetland plants) – Valley Oak, Ryegrass, Mediterranean Barley u US Fish and Wildlife Service uses a wetland classification system that employs indicator species Common Names for Wetland F Marine Systems F Tidal Marshes F Swamps F Freshwater Marshes F Bogs F Prairie Potholes F Wet Tundra F Vernal Pools F Mangroves F Riparian Forest Marshes F Sloughs F Mudflats F Sandflats F Wet Meadows F Playa Lakes F Desert Arroyos F Many Others
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Marine Systems F Open ocean overlying the continental shelf F High energy coastline - impacted by waves and currents F Salinity > 3% with little dilution F Ecosystem function is governed by: – Exposure to waves – Texture of substrate - gravel, sand, silt – Tide cycles and heights – Latitude (temperature, sunlight, etc.) System: Marine Subsystem: Subtidal Class: Rock Bottom Subclass: Bedrock System: Marine Subsystem: Intertidal Class: Unconsolidated Shore Subclass: Sand Estuarine Systems F Deepwater tidal habitats and adjacent tidal wetlands F Semi-enclosed by land F Salinity is variable, 0.5% to 3% occasionally diluted with freshwater runoff F Estuaries and lagoons F Only low energy waves are present System: Estuarine Subsystem: Subtidal Class: Unconsolidated Bottom Subclass: Sand System: Estuarine Subsystem: Intertidal Class: Emergent Wetland Subclass: Non-persistent
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This note was uploaded on 06/07/2009 for the course CEE 4620 taught by Professor Gensler during the Spring '09 term at Georgia Institute of Technology.

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Wetlands - What Are Wetlands? F F F Wetlands Overview...

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